LaNiO3 as a Pt catchment material in the ammonia oxidation process

• Published in: Materials today communications 2022-12, Vol.33, p.104084, Article 104084
• Main Authors: Hessevik, J., Fjellvåg, A.S., Iveland, O., By, T., Skjelstad, J., Waller, D., Fjellvåg, H., Sjåstad, A.O.
• Format: Article
• Language: English
• Subjects: Ammonia oxidation; LaNiO3; N2O decomposition; Nitric acid production; Platinum catchment; Platinum recovery
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2022.104084

Platinum is lost as gaseous PtO2 from the Pt-Rh (typically 95:5 wt%) catalyst used in the ammonia oxidation process. The most common technology utilized today for recovering PtO2 from the gas stream is to apply Pd-Ni (95:5 wt%) catchment gauzes. However, the technology suffers due to loss of Pd at the same time as a severe reconstruction of the alloy creates a large pressure drop during operation. In the search of alternative materials, LaNiO3 is considered as an interesting Pt catchment material. The evaluation is based on lab-scale Pt catchment experiments in a gas flow of dry air using a six-zone furnace with a Pt source placed at 1000 °C to create gaseous PtO2, and LaNiO3 pellets placed downstream at 700 – 900 °C. The duration of the experiments varied from 1 to 26 days, and scanning electron microscopy – energy dispersive X-ray analysis and powder X-ray diffraction were utilized to prove the catchment of Pt. The key finding is that LaNiO3 captures Pt and transforms via the non-stoichiometric rhombohedral LaNi1−xPtxO3 (x ≤ 0.075) and monoclinic La2Ni2−2xPt2xO6 (0.20 ≤ x